FIG. 1 illustrates a wireless communication system 100. Referring to FIG. 1, wireless communication system 100 may include eNodeB (eNB) 110, Relay Node (RN) 120 and User Equipments (UEs) 131 and 132. Hereinafter, UE 131 served directly by eNB 110 is referred to as Macro-UE, and UE 132 served by RN 120 is referred to as Relay-UE. Generally, RN 120 delivers signals from Relay-UE 132 to eNB 110, or signals from eNB 110 to Relay-UE 132. Further, RN 120 supports improvements of wireless communication system 100, such as expanding the coverage of high data rates, group mobility, temporary network deployment, the cell-edge throughput and providing coverage in new areas.
FIG. 2 illustrates links between eNB and RN, and links between RN and UE. Referring to FIG. 2, RN may be wirelessly connected to eNB via Un interface, and radio link between RN and eNB is referred to as Backhaul Link. Backhaul Downlink is a radio link from eNB to RN, and Backhaul Uplink is a radio link from RN to eNB. Further, RN may be wirelessly connected to UE via Uu interface, and radio link between RN and UE is referred to as Access Link. Access Downlink is a radio link from RN to UE, and Access Uplink is a radio link from UE to RN.
Backhaul link may operate in the same frequency band as the access link, which is referred to as ‘In-band.’ On the other hand, backhaul link may operate in different frequency band from the access link, which is referred to as ‘Out-band.’
In case of In-band RN, if receiving backhaul downlink signal and transmitting access downlink signal are performed at the same time on the same frequency band, signal transmitted from the RN transmitter can be received at the RN receiver. Similarly, if RN receives access uplink signal and transmits backhaul uplink signal simultaneously on the same frequency band, signal transmitted from the RN transmitter can be received at the RN receiver. Accordingly, interference occurs due to the RN transmitter causing interference to its own receiver. To avoid such interference, resource partitioning for RN can be considered. Namely, it is required that transmitting and receiving on the same frequency band do not take place simultaneously in RN operation. For resource partitioning, RN may operate in half-duplex mode. For example, In-band RN may transmit backhaul uplink signal in a certain time slot (subframe), and receive access uplink signal in another time slot (subframe). In other words, backhaul link and access link transmission/reception are multiplexed with Time Division Multiplexing (TDM) scheme.